1. Field of the Invention
This invention is directed to a stroke indicator for wellbore apparatus with an inner movable mandrel and for systems for patching a hole or leak in a tubular member in a wellbore; to such systems that expand a liner patch to create a seal; to methods for using such systems; to a two-member tubular patch; and, in one particular aspect, to such a system and methods of its use that can be inserted through a relatively small diameter restriction as is presented by some types of tubing and then into a larger diameter member that has an area to be sealed.
2. Description of Related Art
Oil and gas wells are ordinarily completed by first cementing casing in the hole. Occasionally, a leak develops at some point in the casing and permits the loss of well fluids to a low pressure, porous zone behind the casing, or permits an unwanted fluid such as water to enter the well.
It is sometimes necessary to patch a hole or other defect in oil well pipe such as casing or production tubing by expanding a malleable liner into sealed engagement with the inside wall of the pipe.
A principal use for liners in wells is to avoid the necessity for running an entire string of smaller casing in a well which already has a larger string of casing. Possibly the most common use is in the bottom of the well where the existing casing does not extend to the bottom of the well. In this use, a short liner is lowered through the casing into the bottom of the well where a seal is formed between the liner and casing to provide a metallic liner in the well to substantially its full depth. In such cases a seal between the liner and casing is generally provided by Portland cement pumped in back of the liner to fill the space between the liner and casing. Such seals are seldom perfect. As a result, if the pressure of fluids from the formations penetrated by the well is applied to the outside of the liner and casing, a leak usually results. The liner may not be as thick or strong as the casing. When pressure is applied outside the liner and casing, the liner is compressed more than the casing and a crack forms between them even if none existed before. As soon as an opening is formed for entrance of fluids between the casing and liner, the pressures inside and outside the casing tend to become balanced, permitting the casing to return to its unstressed condition. This further widens the opening between the casing and liner. Since the wider the opening, the more the casing stress is relieved and since the more this stress is relieved, the wider the opening becomes, it is apparent that a leak between the casing and liner can hardly be avoided even though a long overlap of casing and liner is provided. This problem is particularly acute if it is desired to place a steel liner or patching steel sleeve over parted casing or a split or hole in casing. In this case, it is difficult to place Portland cement between the casing and liner and hold the cement in place until it sets. In addition, the application of pressure outside the liner quickly causes leakage in the manner just described.
Pipe such as casing or tubing for oil wells may have variations in the inside wall which reduce or enlarge the inside diameter of the pipe. If such variations are present in an area of pipe which receives a liner, it is desirable to expand the liner to conform to such variations to provide an effective seal between the liner and the pipe. A difficulty encountered in utilizing liner expanding tools in casing or production tubing is in removing the tool after the tool has been driven through the liner. If there are restrictions in the diameter of the pipe in or above the area covered by the expanded liner, there is more likelihood that the tool may hang up at the restriction and possibly even damage the liner as it is pulled therethrough.
Various devices have been devised for setting liners to patch casing, tubing, or oil well pipe. U.S. Pat. No. 3,191,677 discloses liner setting apparatus with an expander ball which is driven through the liner by an explosive jar. U.S. Pat. No. 3,489,220 discloses a method and apparatus for setting a malleable liner having a reverse bend therein over a hole in the pipe, removing a reverse bend from the liner to enlarge the diameter thereof to slightly less than the inside diameter of the pipe and expanding the liner to fit tightly in the pipe.
U.S. Pat. No. 3,785,193 discloses a tool for expanding a liner to fit tightly against the inside wall of a pipe such as oil well casing or tubing in spite of variations in the inside diameter of the pipe. The tool of this invention includes a mandrel that is adapted to be driven through the liner after the liner has been positioned over the hole or other defect in the pipe. A collet having flexible fingers extending therefrom is mounted on the mandrel and resiliently mounted pins extend from the mandrel to urge the fingers outwardly into yieldable engagement with the liner such that the liner is expanded to conform to the inside wall of a pipe. The collet may be mounted for slidable movement with respect to the laterally extending pins so that the flexible fingers can be moved inwardly as the tool is lowered into or removed from the pipe thereby preventing the fingers from damaging the liner or otherwise hanging up in the liner or pipe.
One prior art method of repairing leaks in casing includes placing a steel liner in the well, then expanding it against the inside surface of the casing. The liner is corrugated longitudinally to reduce its diameter so that it will pass through the casing easily. A thin coating of an epoxy resin or other cementing material and a glass cloth mat are applied to the outside of the liner before it is run in the well. The corrugated liner is run in the well on a tubing string, then expanded against the casing by drawing an expander device through the liner with the upper end of the liner resting against the lower end of the tubing. The expander device is moved through the liner by a hydraulic pump, operated by fluid supplied through the tubing. This method of placing the liner sometimes presents problems which contribute significantly to the expense of the operation. One problem is that the tubing string must be pulled and run in the well twice, once to attach the sleeve and setting tool and once to remove the setting tool. Another problem is that weak sections in the tubing sometimes fail under the force of the hydraulic pressure used to operate the expander.
U.S. Pat. No. 3,167,122 discloses a method and apparatus for expanding a steel liner in a casing using wire line equipment after the tubing has been removed from the well, thereby reducing the amount of time necessary to place the liner and avoiding the risk or rupturing the tubing with hydraulic pressure. The corrugated liner is supported on a rod attached to the wire line or cable with the rod passing through the longitudinal axis of the liner and the expander device attached to the rod below the liner. An explosive charge inside the liner is detonated when the liner is opposite the leak in the casing to expand the liner against the casing with sufficient force to anchor the liner so that the expander can be pulled through to complete the expansion of the liner.
FIGS. 1A-1I show a prior art casing patch system co-owned with the present invention. As shown in FIGS. 1A and 1I, the prior art system includes an upper connection for connection to a tubular string above the system (e.g. to a tubing string or coiled tubing) a centralizer, a slide valve, a bumper jar, an anchoring hydraulic hold down, a setting tool including dual hydraulic cylinders (each cylinder has a movable piston therein), extending rods (extending from a polish rod connected to a piston in one of the dual hydraulic cylinders to any extending rod which itself is connected to a safety joint), and an expander assembly that includes a safety joint, a cone, and a collet assembly, and a lower plug or end, e.g. a bull plug. The liner may be a steel liner and is initially located over the polish rod.
As shown in FIG. 1A, the liner has been coated with epoxy resin and the system has been run into casing in a cased wellbore on a working string (e.g. a tubular string or coiled tubing). The liner is positioned adjacent a leak area ("Leak").
As shown in FIG. 1B the working string is raised to close the circulating slide valve. FIG. 1C illustrates the application of hydraulic pressure (e.g. provided by an hydraulic fluid pumping system at the surface which pumps fluid down the working string and to the prior art patch system) which forces out movable buttons on the hydraulic hold down anchoring the system at the desired location in the casing and isolating the working string from tensile loads associated with the setting operation.
As shown in FIG. 1D, hydraulic fluid pressure on the underside of the piston (arrow pointing up) pulls the expander assembly into the bottom of the corrugated liner patch. As pressure increases the expander assembly is forced further into the patch (upwardly) expanding it against the inside of the casing. About four and a half feet of the corrugated liner patch are expanded in one stroke of the setting tool. Then the circulating valve is opened by lowering the working string and telescoping the valve. The working string is raised again to pull up the dual cylinders of the setting tool in relation to pistons held down by the expander assembly. An expanded section of the patch is anchored to the casing wall by friction caused by compressive hoop stress. Hydraulic pressure is again applied to tubing after closing the circulating valve. Hydraulic hold down buttons expanded to anchor the cylinder in a new, higher position.
As shown in FIG. 1E, the expander assembly is again forced through the corrugated patch, expanding it against the inside of casing. This procedure is continued until the entire patch is set. The epoxy resin coating is extruded into leaks or cavities in the casing wall and acts as a gasket and additional sealing agent. Setting time normally requires less than thirty minutes for a twenty foot patch. The tool is then removed from the hole and the patch is pressure tested as required.
A system as shown in FIG. 1A permits limited expansion and contraction of its collet assembly and is not suitable as a "thru-tubing" system or a system to be run through a first relatively small tubular into a relatively larger tubular to be repaired.
Many prior art tubular patches are about twenty feet long and comprise two ten foot patch tubulars welded together at the factory with high quality heat-treated welds. To produce a tubular patch longer than this, multiple pieces are often welded together on a rig. Often such welding can present a safety hazard. Also the shipment of relatively longer tubular patches from the factory to a rig site is usually not practical or economical.
There has long been a need for a casing patch system which is efficient and effective; for a multi-member tubular patch producible at a rig site with no welding or only tack welding; and for a stroke indicator for a tubular expander system. There has long been a need for such a tubular expander patch system which is insertable through a smaller diameter restriction, tubular, or tubular string into a larger diameter tubular, e.g. casing, which has a leak or hole to be repaired. There has long been a need for such a system that is easily releasable and retrievable, particularly in the event of sticking within a liner patch. There has long been a need for such a system that effectively irons out substantially all of a liner patch. There has long been a need for such a system that prevents premature entry of a top cone into a liner to be expanded prior to full extension of a liner expander apparatus.